1. Field of the Invention
The present invention relates to an electronic circuit and electronic equipment, which are suitable for high sensitivity detection of capacity.
2. Description of Related Art
Personal identification by fingerprint matching plays an important role, not only for criminal investigation, but also as a simple and reliable means for prevention of crime and improvement of safety. Japanese Patent Laid-Open No. 8-305832 suggests a finger print sensor for obtaining finger print image pattern electrically, by using the electrostatic capacity value formed between a finger-tip and an electrode, that varies depending on unevenness of fingerprint.
In recent years, made-to-order medical care using bioinformatic technology is proposed in the field of medical science. Demand of a biochip, which can check a lot of samples to be examined with high speed, is increasing as a key technique of bioinformatic technology.
In the above mentioned finger print sensor and biochip, a transistor should be protective with a detection portion in the detection device, in order to implement processing with high speed. However, a transistor, a thin film transistor (TFT) in particular, has large fluctuation of its characteristics, such that it is difficult to implement precise detection. In addition, it is difficult to detect a microscopic amount of capacity.